Structural correlates of language processing in primary progressive aphasia.

Understanding the relationships between brain structure and language behaviour in primary progressive aphasia provides crucial information about these diseases' pathomechanisms. However, previous investigations have been limited from providing a statistically reliable view of broad language abilities by sample size, variant focus and task focus. In this study, the authors aimed to determine the relationship between brain structure and language behaviour in primary progressive aphasia, to determine the degree to which task-associated regions were atrophied across disease variants and to determine the degree to which task-related atrophy overlaps across disease variants. Participants were 118 primary progressive aphasia patients and 61 healthy, age-matched controls tested from 2011 to 2018 in the German Consortium for Frontotemporal Lobar Degeneration cohort. Diagnosis of primary progressive aphasia required progressive deterioration of mainly speech and language for ≥ 2 years, and variant was diagnosed by the criteria of Gorno-Tempini et al. (Classification of primary progressive aphasia and its variants. Neurology. 2011;76(11):1006-1014). Twenty-one participants not fulfilling a specific subtype were classified as mixed-variant and excluded. Language tasks of interest included the Boston naming test, a German adaptation of the Repeat and Point task, phonemic and category fluency tasks and the reading/writing subtest of the Aachen Aphasia Test. Brain structure was measured by cortical thickness. We observed networks of language task-associated temporal, frontal and parietal cortex. Overlapping task-associated atrophy was observed in the left lateral, ventral and medial temporal lobes, middle and superior frontal gyri, supramarginal gyrus and insula. Some regions, primarily in the perisylvian region, were associated with language behaviour despite showing no significant atrophy. The results crucially extend less powerful studies associating brain and language measures in primary progressive aphasia. Cross-variant atrophy in task-associated regions suggests partially shared underlying deficits, whereas unique atrophy reinforces variant-specific deficits. Language task-related regions that are not obviously atrophied suggest regions of future network disruption and encourage understanding of task deficits beyond clearly atrophied cortex. These results may pave the way for new treatment approaches.

Speech Motor Profiles in Primary Progressive Aphasia.

PURPOSE: Previous research on motor speech disorders (MSDs) in primary progressive aphasia (PPA) has largely focused on patients with the nonfluent/agrammatic variant of PPA (nfvPPA), with few systematic descriptions of MSDs in variants other than nfvPPA. There has also been an emphasis on studying apraxia of speech, whereas less is known about dysarthria or other forms of MSDs. This study aimed to examine the qualitative and quantitative characteristics of MSDs in a prospective sample of individuals with PPA independent of subtype. METHOD: We included 38 participants with a root diagnosis of PPA according to current consensus criteria, including one case with primary progressive apraxia of speech. Speech tasks comprised various speech modalities and levels of complexity. Expert raters used a novel protocol for auditory speech analyses covering all major dimensions of speech. RESULTS: Of the participants, 47.4% presented with some form of MSD. Individual speech motor profiles varied widely with respect to the different speech dimensions. Besides apraxia of speech, we observed different dysarthria syndromes, special forms of MSDs (e.g., neurogenic stuttering), and mixed forms. Degrees of severity ranged from mild to severe. We also observed MSDs in patients whose speech and language profiles were incompatible with nfvPPA. CONCLUSIONS: The results confirm that MSDs are common in PPA and can manifest in different syndromes. The findings emphasize that future studies of MSDs in PPA should be extended to all clinical variants and should take into account the qualitative characteristics of motor speech dysfunction across speech dimensions. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.22555534.

Speech and Nonspeech Parameters in the Clinical Assessment of Dysarthria: A Dimensional Analysis.

Nonspeech (or paraspeech) parameters are widely used in clinical assessment of speech impairment in persons with dysarthria (PWD). Virtually every standard clinical instrument used in dysarthria diagnostics includes nonspeech parameters, often in considerable numbers. While theoretical considerations have challenged the validity of these measures as markers of speech impairment, only a few studies have directly examined their relationship to speech parameters on a broader scale. This study was designed to investigate how nonspeech parameters commonly used in clinical dysarthria assessment relate to speech characteristics of dysarthria in individuals with movement disorders. Maximum syllable repetition rates, accuracies, and rates of isolated and repetitive nonspeech oral-facial movements and maximum phonation times were compared with auditory-perceptual and acoustic speech parameters. Overall, 23 diagnostic parameters were assessed in a sample of 130 patients with movement disorders of six etiologies. Each variable was standardized for its distribution and for age and sex effects in 130 neurotypical speakers. Exploratory Graph Analysis (EGA) and Confirmatory Factor Analysis (CFA) were used to examine the factor structure underlying the diagnostic parameters. In the first analysis, we tested the hypothesis that nonspeech parameters combine with speech parameters within diagnostic dimensions representing domain-general motor control principles. In a second analysis, we tested the more specific hypotheses that diagnostic parameters split along effector (lip vs. tongue) or functional (speed vs. accuracy) rather than task boundaries. Our findings contradict the view that nonspeech parameters currently used in dysarthria diagnostics are congruent with diagnostic measures of speech characteristics in PWD.

Profiles of Dysarthria: Clinical Assessment and Treatment.

In recent decades, we have witnessed a wealth of theoretical work and proof-of-principle studies on dysarthria, including descriptions and classifications of dysarthric speech patterns, new and refined assessment methods, and innovative experimental intervention trials [...].

The prevalence of apraxia of speech in chronic aphasia after stroke: A bayesian hierarchical analysis.

Apraxia of speech is a motor speech disorder that occurs after lesions to the left cerebral hemisphere, most often concomitant with aphasia. It requires specific approaches in the study of its physiological and neuroanatomical basis and special expertise in clinical care. Knowing its prevalence in patients with aphasia after stroke is therefore relevant for planning specific resources in clinical research and in health care provision. Systematic studies of the frequency of this condition are lacking. We examined the frequency of apraxia of speech in a representative sample of 156 patients with chronic post-stroke aphasia. Three experts classified the patients' speech by best-practice auditory-perceptual methods. Bayesian hierarchical models were fitted to obtain probability distributions for prevalence estimates. A prior distribution was calculated in two steps, including Bayesian models for published frequency data (step 1) and prevalence estimates from experienced clinicians (step 2). Separate models were fitted for different severity ranges. Overall, a prevalence rate of .44 [.30, .58] was obtained. When only moderate and severe cases were taken into account, the rate was .35 [.23, .49]. After a further restriction to only severe impairment, prevalence dropped to .22 [.12, .34]. Patients identified with apraxia of speech had suffered more severe strokes according to clinical criteria and had more severe aphasias. The presence of apraxia of speech was predicted by the articulation/prosody and syntax rating scales of the Aachen Aphasia Test. Lower prevalence estimates published earlier are probably biased by low sensitivity of assessment instruments for mild speech impairment.

Motor speech disorders in the nonfluent, semantic and logopenic variants of primary progressive aphasia.

OBJECTIVE: Motor speech disorders (MSDs) are characteristic for nonfluent primary progressive aphasia (nfvPPA). In primary progressive aphasia (PPA) of the semantic (svPPA) and of the logopenic type (lvPPA), speech motor function is considered typically intact. However, knowledge on the prevalence of MSDs in svPPA and lvPPA is mainly based on studies with a priori knowledge of PPA syndrome diagnosis. This fully blinded retrospective study aims to provide data on the prevalence of all types of MSDs in a large sample of German-speaking patients with different subtypes of PPA. METHOD: Two raters, blinded for PPA subtype, independently evaluated connected speech samples for MSD syndrome and severity from 161 patients diagnosed with nfvPPA, svPPA or lvPPA in the database of the German Consortium of Frontotemporal Lobar Degeneration (FTLDc). In case of disagreement, a third experienced rater re-evaluated the speech samples, followed by a consensus procedure. Consensus was reached for 160 patients (74 nfvPPA, 49 svPPA, 37 lvPPA). MAIN RESULTS: Across all PPA syndromes, 43.8% of the patients showed MSDs. Patients with nfvPPA demonstrated the highest proportion of MSDs (62.2%), but MSDs were also identified in svPPA (26.5%) and lvPPA (29.7%), respectively. Overall, dysarthria was the most common class of MSDs, followed by apraxia of speech. In addition, we identified speech abnormalities presenting as "syllabic speech", "dysfluent speech", and "adynamic speech". DISCUSSION: Our study confirmed MSDs as frequently occurring in PPA. The study also confirmed MSDs to be most common in patients with nfvPPA. However, MSDs were also found in substantial proportions of patients with svPPA and lvPPA. Furthermore, our study identified speech motor deficits that have not received attention in previous studies on PPA. The results are discussed against the background of the existing literature on MSDs in PPA, including theoretical considerations of the neuroanatomical conditions described for each of the different subtypes of PPA.

The Impact of Dysarthria on Laypersons' Attitudes towards Adults with Cerebral Palsy.

OBJECTIVE: This study investigated laypersons' attitudes towards adults with dysarthria due to cerebral palsy (CP). We aimed to explore the impact of the overall severity and of specific symptoms of dysarthria on laypersons' evaluations. PATIENTS AND METHODS: Eighteen adults with dysarthria due to CP and 6 nondysarthric controls participated as speakers. The individuals with CP underwent dysarthria assessment based on a standardized tool. The results were compared to those of a listening experiment with 20 laypersons. A text passage spoken by all speakers was presented to the listeners, who provided their evaluations using rating scales specifically developed for this study. The tool addressed 3 dimensions of attitudes: (1) estimation of a speaker's cognitive-linguistic abilities; (2) attribution of personality and social characteristics, and (3) listeners' emotions and behavioral tendencies towards the speaker. RESULTS: Severity of dysarthria was strongly correlated with the overall attitudes. Regression analyses identified different symptoms as predictors of the listeners' judgements. CONCLUSION: Severity of dysarthria seems to have a major impact on laypersons' attitudes. Results suggest that speech symptoms may have a very specific influence on laypersons' evaluations. This may be important for clinical care, since symptoms with the most negative impact should be focused on in treatment.

Higher-Faster-Farther: Maximum Performance Tests in the Assessment of Neurogenic Speech Impairment.

BACKGROUND: Maximum performance tests are widely used in dysarthria assessment. From a theoretical perspective, the motor demands of such tasks differ from those of speaking. Therefore, their validity as measures of dysarthric impairment needs to be established empirically. PATIENTS AND METHODS: Maximum phonation time (MPT) and maximum syllable repetition rate (MRR) were compared with sentence reading/repetition tasks. In study 1, 130 patients with neurologic movement disorders and 130 healthy control participants were examined. Presence/severity of dysarthria was measured using psychometrically standardized auditory scales. In study 2, 16 healthy volunteers participated in an experiment designed to examine the intraspeaker variability of MPT, MRR, and sentence repetition across eight trials. RESULTS: Study 1: MPT made no reasonable contribution to the diagnosis of dysarthria or of any specific dimension of perceived speech impairment. MRR correlated with overall speech impairment but turned out to be an insensitive and highly unspecific statistical marker, afflicted with aetiology-specific errors. Study 2: compared with sentence repetition, both MPT and MRR demonstrated highly increased within-subject inconsistencies. CONCLUSION: The validity of MPT and MRR tasks as measures of dysarthria is still unsettled.

The feasibility of assessing speech and non-speech function of the speech apparatus in adults with cerebral palsy.

This short note reports on observations concerning the feasibility of a set of speech and non-speech assessment tasks in an investigation of dysarthria in 21 adults (15 males/6 females; median 23 years) with cerebral palsy and concomitant cognitive impairment. The participants were assessed with nine tasks representing standard components of clinical dysarthria assessment (i.e. six speech and three non-speech tasks). The tasks were evaluated for their feasibility on the basis of common clinical criteria. Our results indicated that, overall, speech tasks were more feasible than non-speech tasks. Several participants showed signs of dysexecutive behaviour on some of the non-speech tasks, but not on the speech tasks. The current note provides tentative clues regarding the impact of cognitive deficits on the feasibility of assessment tasks in the diagnosis of dysarthria.

Gauging the Auditory Dimensions of Dysarthric Impairment: Reliability and Construct Validity of the Bogenhausen Dysarthria Scales (BoDyS).

Purpose: Standardized clinical assessment of dysarthria is essential for management and research. We present a new, fully standardized dysarthria assessment, the Bogenhausen Dysarthria Scales (BoDyS). The measurement model of the BoDyS is based on auditory evaluations of connected speech using 9 scales (traits) assessed by 4 elicitation methods. Analyses of the BoDyS' reliability and construct validity were performed to test this model, with the aim of gauging the auditory dimensions of speech impairment in dysarthria. Method: Interrater agreement was examined in 70 persons with dysarthria. Construct validity was examined in 190 persons with dysarthria using a multitrait-multimethod design with confirmatory factor analysis. Results: Interrater agreement of < 1 on a 5-point scale was found in 91% of cases across listener pairs and scales. Average reliability was .85. Inspection of the multitrait-multimethod matrix pointed at a high convergent and discriminant validity. Modeling of the BoDyS trait and method factors using confirmatory factor analysis yielded high goodness of fit. Model coefficients confirmed high discriminant and convergent validity and revealed meaningful relationships between scales and methods. Conclusions: The 9 auditory scales of the BoDyS provide a reliable and valid profile of dysarthric impairment. They permit standardized measurement of clinically relevant dimensions of dysarthric speech.

Dissociating oral motor capabilities: Evidence from patients with movement disorders.

Abnormal articulation rate is a frequent symptom in neurogenic speech disorders. Performance rates in speech-like or nonspeech tasks involving the vocal motor apparatus are commonly accepted predictors of speech motor function in general and of articulation rate in particular. However, theoretical arguments and behavioral observations in populations with disordered speech indicate that different oral motor behaviors may be governed by distinct mechanisms. The objective of the present study was to expand our knowledge of the relationship between speech movements, on the one hand, and speech-like and nonspeech oral motor behaviors, on the other, by using a rate paradigm. 130 patients with neurological movement disorders of different origins and 130 neurologically healthy subjects participated in the study. Rate data was collected in a speech task (oral reading/repetition), in speech-like tasks (rapid syllable repetitions), and in nonspeech tasks (rapid single articulator movements of the tongue/lips). The main analyses involved a multiple single-case method, by which we tested for differences among each patient's performance rates on the three task types. The results disclosed statistically significant (classical and strong) dissociations between movement rates obtained from the speech task and those obtained from speech-like and nonspeech oral motor tasks in a number of patients. The findings can be interpreted as reflecting major differences in task demands and underlying control mechanisms. The validity of diagnostic indices for speech obtained from speech-like or nonspeech tasks must thus be called into question.

Oral Motor Abilities Are Task Dependent: A Factor Analytic Approach to Performance Rate.

Measures of performance rates in speech-like or volitional nonspeech oral motor tasks are frequently used to draw inferences about articulation rate abnormalities in patients with neurologic movement disorders. The study objective was to investigate the structural relationship between rate measures of speech and of oral motor behaviors different from speech. A total of 130 patients with neurologic movement disorders and 130 healthy subjects participated in the study. Rate data was collected for oral reading (speech), rapid syllable repetition (speech-like), and rapid single articulator movements (nonspeech). The authors used factor analysis to determine whether the different rate variables reflect the same or distinct constructs. The behavioral data were most appropriately captured by a measurement model in which the different task types loaded onto separate latent variables. The data on oral motor performance rates show that speech tasks and oral motor tasks such as rapid syllable repetition or repetitive single articulator movements measure separate traits.

Dysarthria in Adults With Cerebral Palsy: Clinical Presentation and Impacts on Communication.

PURPOSE: Although dysarthria affects the large majority of individuals with cerebral palsy (CP) and can substantially complicate everyday communication, previous research has provided an incomplete picture of its clinical features. We aimed to comprehensively describe characteristics of dysarthria in adults with CP and to elucidate the impact of dysarthric symptoms on parameters relevant for communication. METHOD: Forty-two adults with CP underwent speech assessment by means of standardized auditory rating scales. Listening experiments were conducted to obtain communication-related parameters-that is, intelligibility and naturalness-as well as age and gender estimates. RESULTS: The majority of adults with CP showed moderate to severe dysarthria with symptoms on all dimensions of speech, most prominently voice quality, respiration, and prosody. Regression analyses revealed that articulatory, respiratory, and prosodic features were the strongest predictors of intelligibility and naturalness of speech. Listeners' estimates of the speakers' age and gender were predominantly determined by voice parameters. CONCLUSION: This study provides an overview on the clinical presentation of dysarthria in a convenience sample of adults with CP. The complexity of the functional impairment described and the consequences on the individuals' communication call for a stronger consideration of dysarthria in CP both in clinical care and in research.

How Does GPi-DBS Affect Speech in Primary Dystonia?

BACKGROUND: Globus pallidus internus deep brain stimulation (GPi-DBS) can be an effective treatment for primary dystonia. However, speech disorders have previously been reported as a common possible side effect of the treatment. OBJECTIVES: To study possible deterioration of speech after GPi-DBS and describe this in different dimensions. METHODS: Speech was systematically evaluated in 15 patients with predominant torticollis and GPi-DBS. Each patient was tested twice within one day in two stimulation conditions: ON-DBS vs. OFF-DBS. Speech analyses comprised both function-oriented (perceptual scales, acoustic analyses) and communication-related measures (intelligibility, naturalness). A control sample of 15 healthy speakers underwent the same speech assessment. RESULTS: On the group level, patients with dystonia showed mild but significant impairment on the overall dysarthria scale, the intelligibility score, and the naturalness ratings in both stimulation conditions (Mann-Whitney, P < .05). No stimulation-induced deterioration was found. A slight increase in articulation rate was measured in the ON condition. On the single-case level, effects of GPi-DBS on speech were heterogenous. In one patient we observed a deterioration of speech (dysarthria), in a second patient with a history of childhood stuttering we found an aggravation of dysfluency. Impressive benefits could be documented in another patient who also suffered from spasmodic dysphonia. CONCLUSIONS: The study provides evidence that speech impairment is not a necessary side-effect of GPi-DBS in primary dystonia. Both, recurring of stuttering and a worsening of dysarthria may be seen in individual patients. The positive effects of GPi-DBS on the symptoms of spasmodic dysphonia merits further research as DBS is not commonly applied in this population.

Apraxia of speech: concepts and controversies.

PURPOSE: This article was written as an editorial to a collection of original articles on apraxia of speech (AOS) in which some of the more recent advancements in the understanding of this syndrome are discussed. It covers controversial issues concerning the theoretical foundations of AOS. Our approach was motivated by a change of perspective on motor speech that has taken place in neurobiology, neurolinguistics, phonology, and phonetics during the past few decades. METHOD: The literature on AOS is reviewed from 3 different but overlapping perspectives-that is, a disconnection, a motor memory, and a fine motor skill perspective. Separate sections are devoted to the delimitations of AOS from oral facial apraxia, dysarthria, and phonological impairment. CONCLUSIONS: We conclude that many of the still unresolved conceptual issues about AOS arise from an underspecification of existing models of spoken language production. We suggest that phonological and motor impairments of sound production should be studied by an integrated approach.

Error variability in apraxia of speech: a matter of controversy.

PURPOSE: Error variability has traditionally been considered a hallmark of apraxia of speech (AOS). However, in some of the current AOS literature, relatively invariable error patterns are claimed as a mandatory criterion for a diagnosis of AOS. This paradigm shift has far-reaching consequences for our understanding of the disorder and for its (differential) diagnosis. Against the background of this controversy, the present article aims to further examine error variability in AOS. METHOD: Four patients with relatively pure, mild-to-moderate AOS participated in the study. They repeated 8 target words in 2 different phrase contexts, 10 times each. Error analyses were based on phonetic transcription. Error variability was determined using several measures of (a) consistency of error occurrence and (b) consistency of error type. RESULTS: All patients produced highly inconsistent reactions across multiple trials in some of the target words. However, other words were more consistently accurate or inaccurate. Several factors influencing error variability were identified. CONCLUSIONS: Because this study has disclosed clear indications of variable behavior in AOS, diagnostic guidelines claiming error consistency as a mandatory criterion cannot be maintained. Because error variability is difficult to operationalize, we recommend to no longer use (in)consistency as a strict diagnostic marker of AOS.